Question

OO Object Associations

Aggregation Vs. Composition 

Built-in libraries and functions 

You are required to write a program that implements the computerized maintenance of your monthly expenditure record keeping. You will have to build two classes 1. ExpenseItem, ExpenseLedger 

The class ExpenseLedger will record all the expenses you make. You record an expense by giving it a serial number, a description (that tells what it is about) and the money you spent on this item. So you need to create a class ExpenseItem with serial, description and amount. Provide constructors, getters and setters. Also provide toString for this class. Now in the ExpenseLedger class you need to build a collection that will hold the instance of ExpenseItem. Provide the following methods in the ExpenseLedger

 1. void addExpense(description, amount): You should be able to figure out the serial of the expense yourself. This method will create an expense item and add it to the ledger

 2. int removeSmallExpenses(double amt):This method will find the expense items that are smaller or equal to the amount amt and then remove these items from the list. Note that multiple items can be smaller than this value and thus each of these should be removed. Also this method should return the number of items removed.

 3. double totalExpenditure(): This method will calculate the total expenditure recorded in the ledger so far. You can do this by iterating through the expenses list and adding all the amounts to find the total expenditure so far.

 4. Override the toString method so that the ledger is printed in a well formatted way

 Main class will be provided to you, your code must run and produce the desired output. This will be a check of your correct implementation. Please use the names of classes and methods as provided in this description.

Answer 1

ExpenseItem.java

public class ExpenseItem {

    private int serialId;

    private String description;

    private double amount;

    

    public ExpenseItem(int serialId, String description, double amount) {

        this.serialId = serialId;

        this.description = description;

        this.amount = amount;

    }

    

    public int getSerialId() {

        return serialId;

    }

    

    public void setSerialId(int serialId) {

        this.serialId = serialId;

    }

    

    public String getDescription() {

        return description;

    }

    

    public void setDescription(String description) {

        this.description = description;

    }

    

    public double getAmount() {

        return amount;

    }

    

    public void setAmount(double amount) {

        this.amount = amount;

    }

    

    @Override

    public String toString() {

        return String.format(" %10d  %30s  %10.2f \n",getSerialId(),getDescription(),getAmount());

    }

}

ExpenseLedger.java

import java.util.ArrayList;

import java.util.Iterator;

public class ExpenseLedger {

    private static int serialId = 1;

    private final ArrayList records;

    

    public ExpenseLedger() {

        this.records = new ArrayList();

    }

    

    public void addExpense(String description, double amount) {

        records.add(new ExpenseItem(serialId++, description, amount));

    }

    

    public int removeSmallExpenses(double amt) {

        Iterator itr = records.iterator();

        int hadInitially = records.size();

        while (itr.hasNext()) {

            if (((ExpenseItem) itr.next()).getAmount() <= amt) {

                itr.remove();

            }

        }

        return hadInitially - records.size();

    }

    

    public double totalExpenditure() {

        double total = 0.0;

        for (ExpenseItem record : records) {

            total += record.getAmount();

        }

        return total;

    }

    

    @Override

    public String toString() {

        StringBuilder data = new StringBuilder("");

        for (ExpenseItem record : records) {

            data.append(record.toString());

        }

        return String.format("|%10s| %30s| %10s|\n", "Serial ID", "Description", "Amount")

        + String.format("-%10s--%30s--%10s-\n", "----------", "------------------------------", "----------")

        + data;

    }

}

Main.java

public class Main {

    public static void main(String[] args) {

        ExpenseLedger expenseLedger = new ExpenseLedger();

        expenseLedger.addExpense("TV",30);

        expenseLedger.addExpense("Twitch",40);

        expenseLedger.addExpense("Electricity",150);

        expenseLedger.addExpense("Internet",100);

        System.out.println(expenseLedger);

        System.out.println("Number of items removed having less than equal to Amount 30.00 is " + expenseLedger.removeSmallExpenses(35));

        System.out.println(expenseLedger);

        System.out.println("Total expenditure = " + expenseLedger.totalExpenditure());

    }

}